Problem: Fluorescent Light Source

Reason: The chief difference between tungsten and daylight sources is nothing more than the proportion of red and blue light. The spectrum of colors is continuous, but is biased toward one end or the other. However, some types of fluorescent lights produce illumination that has a severe deficit in certain colors, such as only particular shades of red. If you looked at the spectrum or rainbow of colors encompassed by such a light source, it would have black bands in it, representing particular wavelengths of light. You can't compensate for this deficiency by adding all tones of red, either digitally or with a filter that is not designed specifically for that type of fluorescent light. Figure 6.14 shows an image that was exposed under fluorescent lights using a tungsten light balance.